Most frame projects hit the same wall at the ordering stage. The drawing says 2020, the quote says 2020, and the T-nuts still will not seat. The profile name only describes the outside size. It tells you nothing about slot width, wall thickness, or which measurement system the supplier uses.
A 2020 aluminum extrusion is a square structural profile with a nominal cross-section of 20 mm x 20 mm and a T-slot down each face. On a standard part the wall thickness lands between 1.2 and 1.5 mm, and the slot opening sits close to 6 mm. Those numbers are not fixed by the name. They come off the custom aluminum extrusion dies behind the profile, which is why two suppliers can both ship a 2020 and still disagree on the slot.
Below is what a standard 2020 profile actually measures, how the size system works, and what to confirm before placing an order.
What are the dimensions of a 2020 aluminum extrusion
A 2020 profile measures 20 mm by 20 mm on the outside and carries one T-slot on each of its four faces. The slot opening is about 6 mm, the wall sits between 1.2 and 1.5 mm, and the weight runs around 0.45 to 0.55 kg per meter.
That is the headline spec. The details that decide whether hardware fits are in the table below.
| Parameter | Typical value | Notes |
|---|---|---|
| Cross-section | 20 mm x 20 mm | Nominal outer size, width by height |
| Slot opening | About 6 mm | Supplier sheets list 5.4 mm to 6.2 mm |
| Inner channel width | Roughly 10 to 12 mm | Must clear the T-nut head |
| Wall thickness | 1.2 to 1.5 mm | Heavier-wall versions are available |
| Weight | About 0.45 to 0.55 kg/m | Drops as the wall gets thinner |
| Alloy and temper | 6063-T5 | 6061 is used where more strength is needed |
| Stock lengths | 1 m, 2 m, 3 m, 6 m | Custom cutting is standard |
| Cut tolerance | Around 0.5 mm on custom lengths | Confirm with the supplier |
| Dimensional tolerance | EN 755-9 commercial, DIN EN 12020-2 precision | Tighter tolerance costs more |
Supplier specification data, checked 12 October 2026. Actual values vary by design, so treat the table as a comparison baseline rather than a promise.
Slot opening and groove depth
The slot opening causes most fit problems. A standard 2020 opening sits near 6 mm and accepts M4 and M5 T-nuts, including slide-in and drop-in types. Inner channel width usually runs 10 to 12 mm, which gives the nut room to rotate and lock.
A 5.4 mm opening looks close to 6 mm on a drawing. In practice it will not take hardware built for a 6 mm slot without force, and forcing a nut damages both parts. If profiles and accessories come from different suppliers, compare the two spec sheets instead of trusting the shared 2020 label.
Wall thickness, weight, and length tolerance
Wall thickness on a standard 2020 usually falls between 1.2 mm and 1.5 mm. Thicker walls add stiffness and weight, and aluminum is priced by weight, so the change shows up on the invoice as well as on the scale. A lighter-wall part suits a small enclosure. It is a poor choice for a load-bearing beam.
Stock lengths are commonly 1 m, 2 m, 3 m, and 6 m, with mill lengths close to 6 m. Custom cutting is normal, and the usual tolerance is around 0.5 mm. Where a profile has to assemble against machined parts, ask for precision dimensional tolerance under a standard such as DIN EN 12020-2 rather than the commercial EN 755-9 default.
2020 t-slot profile types
Most 2020 profiles use a four-slot T-slot design, but the same 20 mm square also comes with V-shaped grooves for linear motion and in a few single-slot or two-slot versions built for tight corners.
Standard T-slot and V-slot
A standard 2020 T-slot has four identical T-shaped channels, one per face. Fasteners slide in from the end, and a bolt clamps through the nut to hold brackets, panels, or joining plates. It is the default part for static frames.
A V-slot 2020 replaces the T profile with a V groove. That groove is shaped to guide wheels and linear bearings directly on the extrusion, so it suits moving carriages, sliding doors, and adjustable fixtures. The two types are not interchangeable once motion hardware is involved. V-slot parts take some T-slot accessories, but the fit is looser and clamping is less reliable.
Rectangular 20-series profiles
The 20 series also covers rectangular sections such as 2040 and 2060. These keep the 20 mm slot and the same 6 mm opening, so brackets and nuts from a 2020 build carry over. The taller section raises stiffness in one direction, which matters on long unsupported spans.
Profiles from different series do not mix as easily. A 20-series nut will not seat in a 30- or 40-series slot, and brackets are sized for one slot width only. Keep one slot series across a frame, and the accessory list stays short.
How the 20 x 20 cross-section is made
The cross-section is produced by hot extrusion. A heated aluminum billet is pushed through a shaped die, and the die opening sets the outer size, the wall thickness, and the slot geometry in a single pass.
Billets are heated to roughly 400 to 500 degrees Celsius before the press pushes them through the die. The emerging profile is quenched, stretched straight, and cut to length. The Aluminum Extruders Council covers the process, alloy selection, and tolerance practice in its Aluminum Extrusion Manual, the reference most designers start from.
This is where the same-name, different-size problem starts. The outer 20 mm is easy to hold. Slot opening and wall thickness depend on how the die bearing and metal flow were designed. Two dies can both produce a legal 20 mm square and still differ by a few tenths of a millimeter inside the slot, which is enough to change whether a drop-in nut seats by hand or needs a mallet.
2020 vs. 8020 aluminum extrusion: what the numbers mean
The two names usually point at different measurement systems. In metric naming, 2020 means a 20 mm square. In the fractional naming common in North America, 2020 means a 2-inch square, close to 50.8 mm.
That single difference sits behind most of the confusion. A buyer searching for 2020 aluminum extrusion can land on a 20 mm metric profile or a 2-inch fractional one, and the two are not close in size, weight, or load capacity. The fractional system counts in inches and uses labels such as 1010 for 1 inch and 1515 for 1.5 inches. The metric system counts in millimeters and uses 2020, 3030, and 4040. Both are widely used, which is why 8020 aluminum extrusion has become loose shorthand for the whole modular T-slot category rather than one size. This note on 80/20 aluminum extrusion walks through how the series labels are applied.
The practical rule is simple. Order against a drawing that shows the cross-section, and write the slot width and tolerance into the request. The name alone is not a specification.
1010 vs. 2020 extrusion sizes
In the metric range, 1010 means a 10 mm x 10 mm section with a slot around 4 mm, and 2020 means a 20 mm x 20 mm section with a slot around 6 mm. In the fractional range, 1010 means 1 inch square, and 2020 means 2 inch square. Same labels, two very different scales.
| Label | Metric section | Metric slot | Fractional section | Fractional slot |
|---|---|---|---|---|
| 1010 | 10 mm x 10 mm | About 4 mm | 1 in x 1 in (25.4 mm) | About 6 mm |
| 2020 | 20 mm x 20 mm | About 6 mm | 2 in x 2 in (50.8 mm) | About 8 mm |
Supplier and distributor catalog data, checked 12 October 2026.
The gap in stiffness is larger than the gap in size. In a published distributor catalog, a 1-inch fractional profile carries a moment of inertia of 0.045 in⁴ (1.872 cm⁴) at 0.529 lb/ft (0.787 kg/m). The 2-inch version jumps to 0.543 in4 (22.589 cm4) at 1.482 lb/ft (2.205 kg/m). More than twelve times the bending resistance for under three times the weight.
That difference decides the application. Light fixtures, small sensor mounts, and printer enclosures sit well inside the smaller section. Anything that spans a gap, carries a load, or gets pushed during use belongs on the larger one.
2020 aluminum extrusion accessories and connectors
The accessories for a 2020 profile are all built around the 6 mm slot, and they only fit a matching slot series. Match the slot first, and the rest of the list is straightforward.
- T-nuts and drop-in nuts in M4 and M5 slide into the channel and take a bolt. Drop-in versions seat without end access, which matters on closed frames.
- Corner brackets and angle gussets join two profiles at 90 degrees and carry most of the load in a static frame.
- End fasteners thread into or press into the profile end, giving a joint that keeps the outer faces flush.
- Panel clips hold acrylic, polycarbonate, or composite sheet inside the slot.
- Joining plates and linear hardware handle in-line connections and V-slot motion setups.
Two habits prevent returns. Confirm the slot width before ordering, and keep one slot series across the whole build. A 20-series bracket will not fit a 40-series slot, however similar the profiles look on screen.
What 2020 aluminum extrusions are used for
A 2020 profile suits light and medium-duty framing where parts need to move, change, or come apart again. It is not a replacement for a welded steel base.
- Machine and automation frames for sensors, small actuators, and conveyors
- Safety guarding, machine enclosures, and protective covers
- Workbenches, assembly tables, and adjustable workstation frames
- Fixtures, inspection jigs, and positioning structures
- Desktop CNC and 3D printer frames
- Display stands and retail structures that get reconfigured
The shared trait is load and span. A 2020 frame handles distributed loads and short spans well. Long unsupported beams, vibration, and heavy point loads call for a larger section such as 3030 or 4040, or for a 2040 oriented so the tall side resists the bend.
Aluminum extrusion price: what drives cost on a 2020 profile
Cost on a 2020 profile comes from four places: raw material, extrusion processing, surface treatment, and secondary machining. Published 2026 supplier guides put standard 6063 profiles at roughly $2.50 to $3.80 per kilogram, with raw aluminum the largest single share.
Those guides also track London Metal Exchange aluminum between $1,500 and $3,500 per tonne across 2025 and 2026, which is why quotes move with the metal market instead of staying flat. Finishing adds more. Anodizing and powder coating are priced per unit and lift the total, while mill finish stays the lowest.
The cost sits apart from all of this. A profile die is a one-time tooling charge, not part of the per-kilo rate, and its effect on unit price depends on order volume. A $2,500 die spread over 5 tonnes adds about $0.50 per kilogram. Spread the same die over 50 tonnes, and the contribution falls to roughly $0.05 per kilogram. Published supplier benchmark, checked 12 October 2026.
That is why small custom runs look expensive per piece and large repeats look cheap. The metal has not changed. The tooling simply has fewer parts to sit on.
Frequently asked questions
Can you weld 2020 aluminum extrusions instead of using connectors?
Yes, with the right process. 6063 welds cleanly once the oxide layer is removed and a filler matched to the alloy is used, though some strength is lost near the weld. Welding also removes the reason most people choose extrusion in the first place: the ability to take the frame apart and rebuild it. On anything likely to be reconfigured, connectors stay the better choice.
How far can a 2020 profile span before it sags?
There is no single answer, because deflection depends on span, load, wall thickness, and how the beam is supported. Calculate it rather than guess. Take the moment of inertia from the profile spec sheet, apply the load case you expect, and check the result against the limit your machine can tolerate. If the number is close, step up to a 2040 or 3030 section before the build starts.
Will 20-series accessories fit other extrusion series?
No. Accessories are sized to a slot series. A 20-series nut and bracket are built for a slot around 6 mm and will not seat in a 30- or 40-series channel. Panel clips are a little more forgiving, but load-bearing joints are not. Confirm the series on both the profile and the hardware before ordering.
